Presence of nonimpacted third molars affects the response of neighboring teeth to nonsurgical periodontal therapy

The second molar is crucial for chewing, but it is often lost due to periodontitis. Periodontal treatment for the second molar is not always effective, and many factors contribute to this. One factor that has gained attention is the impact of a nonimpacted third molar on the periodontal health of the adjacent second molar. In this study, we examined how the presence of a nonimpacted third molar affects the outcome of nonsurgical periodontal therapy for the second molar. We analyzed 776 second molars from 268 patients. The results showed that when the nonimpacted third molar was absent or removed during periodontal therapy, the second molar's condition improved more than when the nonimpacted third molar was present. The data indicated that even with nonsurgical periodontal treatment, the periodontitis of the second molar could not be effectively controlled if an adjacent nonimpacted third molar was present. Therefore, the negative impact of the nonimpacted third molar should be considered to prevent the loss of the second molar.